In industrial automation, wireless arrangements may be used when it is not desirable or feasible to use cables (e.g., because of distance, installation limitation, etc.). However, there are a limited number of solutions available for use in hazardous areas. Known solutions involve the use of an explosion-proof box where the radio transceiver is mounted and the antenna is “attached” to the explosion-proof box.
The signal strength indicators of these arrangements are not designed for hazardous areas. For example, cellular modems (mobile broadband modems, also known as a connect card or data card) need high power for transmitting data over the cellular network, and during fault scenarios the maximum power in the cellular module can go very high (e.g., 6W). Accordingly, in order to operate in hazardous area the entire transceiver other than the antenna needs to be potted so as to prevent direct exposure of the electronics to the hazardous environment.
A Smart Identity Module (SIM) card is a pocket-sized card with embedded integrated circuits that may be included in the transceiver, such as for access authorization to secure areas in industrial automation. The SIM card is conventionally potted with the other transceiver components. There are some devices with the SIM cards being unpotted, however such devices may not meet telecommunications interface standards such as the European Telecommunications Standards Institute (ETSI) standard requirements because of poor signal quality (e.g., too high a signal rise/fall time to the SIM card).